


Cabin Above-ground

by Underwraps



Category: Undertale (Video Game)
Genre: Bondage, Choking, Daddy Kink, Dom/sub, Drug Use, Established Relationship, Explicit Sexual Content, F/F, F/M, Knotting, Multi, Multiple Endings, Multiple Orgasms, Orgy, Polyamory, Praise Kink, Reader has female parts, Reader-Insert, Sex, Sex Toys, Sexual Humor, Size Kink, Smut, Soul Sex, Soulmates, Threesome - F/M/M, Undertale+Underfell+Underswap+Swapfell+Beasttale+Outertale+Lusttale+Dancetale+Horrortale
Language: English
Status: In-Progress
Published: 2020-03-07
Updated: 2020-03-07
Packaged: 2021-03-01 05:20:19
Rating: Explicit
Warnings: Rape/Non-Con
Chapters: 1
Words: 2,062
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23049946
Author URL: https://archiveofourown.org/users/Underwraps/pseuds/Underwraps
Summary: Set a bit after Existence Strikes Back, you and Sans have a party after finishing the house. As your sole boyfriend yet one of many soulmates/links, all the Gasters decide to rig this celebration as much as possible so their sons can woo you over. This story was inspired by "The Cabin in the Woods".
Relationships: Muffet (Undertale)/Reader, Papyrus (Undertale)/Reader, Reader/Everyone, Sans (Undertale)/Reader, W. D. Gaster/Reader
Comments: 12
Kudos: 38





	Cabin Above-ground

Hey, Underwraps here! This is a mini series off my main story, Existence Strikes Back (yes I’m bad at naming)!  **If you don’t want any spoilers to the main series, please avoid this story.** I also recommend reading chapter 18 and 19 of that series if you want to understand their personalities better.

The names of the AU Gasters are as follow:

Original (Orig), Classic

Crimson (Crim), Underfell

Tidepod (Tide), Underswap [GET IT CAUSE HE’S ORANGE AND BLUE, HAH.]

Cut-Throat (Cut), Swapfell

Samba (no nickname), Dancetale

Fang (no nickname), Beasttale

Richard (Rich), Lusttale [RICHARD AKA. DICK]

Nebula (Neb), Outertale

**THIS IS YOUR LAST CHANCE BEFORE SPOILERS SO LOOK AWAY!**

Bravo (Brav), Horrortale Gaster

Congrats to those who guessed who he was correctly! 

Gaster’s POV

“The camera set up is complete. Call out your delegated roles.” Gaster commanded his fellow goop men.

“Crim. Microphones done.” Crimson had his eyelights completely set on his computer, determined to win. The once arrogant monster had full attention to the noises on the other side. To lose was to  **die** . 

“Tide! Heart monitor good!” The orange and blue mess of optimism bursted out from under a desk before popping a monster candy in his mouth. He was excited. His bets were placed in, but with all the competition, the chances were still extremely low. Of course, a  **risky game** made it so much more fun!

“No need to scream, cunt. Cut-Throat. Aerosol canisters set.” He shouted aggressively from behind another screen. Cut was already on edge and Tide shouting was not helping the booming headache that was a product of stress. He was not ready for this literal clusterfuck. Neither did he like his odds for winning. Less than 10%. Losing would  **erase his will** .

“Richie~~~ medicine ready ;)” Richard was… turned on. He liked these kinds of things a bit too much. With his pride and sanity on the line, his only option was to  **pray** .

“Nebula. Area reseted.” Neb had a calm face unlike his other comrades, but it was quite the opposite on the inside. He could barely grasp this ‘game’ to begin with. The added factors and complexity of its nature made it impossible to predict. His nervousness was **eating** **him** **inside out**.

“Fang. Layout finished.” The wolf-like monster grinned with ease. He wasn’t too scared of the penalties. If he and his sons were fed, then that was all that mattered, but perhaps **breaking** **all** **of** **them** wouldn’t be too bad either.

“Samba here! Exits and rooms secured.” The dancer, who was breaking a sweat from stress, began trotting around the surveillance room. His energy was boundless and the tension made it so much worse. One slip-up could **cost** **him** **everything**.

“Bravo,” He sighed at the immaturity of this whole competition. “Bets have been placed.” He gave a tired look to Orig as a cue to start his speech to the rest of his acquaintances.

“Let us begin. Activate the monitoring systems, aphrodisiacs and impairment drugs. May the best father win.”

Your POV

You felt hotter than usual. Almost feverish. And incredibly horny. Then again, it had been a whole month since you banged Sans (AKA Classic). Since the other AUs came in, privacy became negligible and so did your free time. Caring for each individual’s needs was a tiring yet fulfilling job. And finally, you guys had finished an above ground house for you and your two main vertebaes, complete with a proper bathroom! Of course, this whole achievement gave root to more problems. Having 18 separate soulmates kinda does that… BUT YOU WERE DETERMINED TO GET THROUGH! You had finished decorating the humble cottage to see Sans from the front window, standing in the snow with a bag of goods, soaking the sun with a fulfilled expression. Ever since you escaped the underground, Sans would often zone out, overwhelmed with contentment. It was the most delightful sight to see.

“Bonefriend!” You exit the house and give a running hug to your precious tubby skeleton. The impact sends him stepping back a couple steps but the endearing smile reflects his own happiness.

“jeez, babe. you could’ve killed me there.” He shows you that beloved grin before leaning to endow you a little skeleton peck on your forehead. “gotcha the snacks. muffet was nice enough to give extra, but only ‘cause you invited her.” You hum in agreement and pure happiness, grabbing onto his jacket like it was your lifeline, the usual scent of tomato sauce filling your nose. He chuckles at the gesture, possessively opening his jacket to basically smother you. “you know, while the competition is fun and all,” His tone becomes devilish as he zips up his jacket with you in it. “we haven’t been able to fit,” When you realise you’re trapped with him in his jacket, he already had his arms secured around your waist, a blush forming on your cheeks. “any time for-”

“SANS!” Ah, the sound of the confident and awesome Papyrus became clearer by the second. Your captor sighs in slight annoyance before giving you a cheeky smile. ‘Time to run!’ You try to duck out of his jacket, but the sturdy grip made it futile.

“hey bro.”

“SANS, WHERE IS THE HUMAN? I NEED THEIR PERMISSION TO INVITE SOMEONE.” Oh poor Papyrus, he is oblivious to you laughing/jumping from within Sans’ jacket.

“do you want me to  _ marrow  _ it down for you?” Sans lets you go for a second, giving you the chance to pop out of the head hole of his jacket as well.

“HUMAN!!” Papyrus surprisingly ignores the horrible pun and brings you into a wholesome hug. And by bringing you into a hug, Sans too was brought into the goofy embrace.

“Hey Paps. Glad to see you so lively. What do you need?” You’re still giggling a bit from both Sans’ pun and the fact you were in a skeleton sandwich.

“PERMISSION TO INVITE BLUEBERRY, ELDER SIBLING OF STRETCH!” He steps back and speaks to you in a respectful tone while saluting, oblivious to how stupid you must’ve look sharing Sans’ jacket.

“no.” “Granted.”

You and Sans look at each other while Papyrus triumphantly smiles.

“THANK YOU, MAGE!” The prideful skeleton strides off with excitement, ignoring Sans’ pleas for him to wait.

“babe…” Sans finally lets you free from jacket prison, giving you some personal space for a bit. “if we invite one pair, all the others will come.” You see his smile droop a bit at the thought.

“I know, but this is also a great chance for Paps to make new friends, isn’t it?” You reach up to his round cheek bones.

“yeah, but i’m worried for you.” He leans into your hand and holds it as if it were porcelain, mumbling his worries while giving butterfly kisses to your palm. “i don’t want to lose you again.” He broods on all the close calls you had since arriving before looking you right in the eyes, his smile looking more like a frown.

“I know, but we made it and now we have a house! Hey, if I can’t handle it, you can just save me again, right?” You knock him out of his thoughts with a pleasant smile to show your trust. You wanted to show him that it was alright. The past was finally the past. You got through all of it. And, most of all, that you loved him.

“only for you, babe.” He replies with the most charming response that you couldn’t help but kiss him with joy. It is a short kiss that leaked love and gratitude, yet left you breathless. “babe?” 

“Hm?” You look at him inquisitively, wondering what he wanted.

“i didn’t know you were such a good  _ jumper _ .” He flings the horrible pun with his usual grin, causing you to giggle before judging the joke’s worthiness.

Gaster’s POV

“Operation in progress. Bets have been finalised. Kowalski, analysis.” Orig commanded in the room despite no one going by that name (it’s the smart penguin from Madagascar).

“Is this another simulation joke?” Bravo questioned the weird lines, then again, being a crazy scientist did that to you.

“Yes, and now it will be a regular thing.” Orig was cocky to say the least. He had an outrageous advantage, having created the mage AND their relationship with Sans but due to that, was ‘disqualified’ from the competition.

“Lo and behold, we have no leading bets.” Bravo sarcastically presents the board, showing each Gaster had put their money on the more mature sibling from their universe. Even Bravo had his bet riding on his Sans despite the latter’s… hobbies. No father was going to doubt their son’s ability.

“Time to show the data.” Gaster threw the sheet off the biggest screen in the room, uncovering the intricate statistics and most likely ‘routes’ you will take. Sans was in the lead by a landslide at 95%, the rest ranging from 0.1 to 1%. The whole room erupts in groans and complaints at the sight. “Of course, Classic Sans will be removed from the scene, so the chances have been redrawn to…” He clicks on a mouse, the screen twitching with information. 75% chance they all fail.

“Why didja raise them as a killjoy?!” Cut shouted angrily at Orig, appalled by the odds.

“Yeah! Their knowledge of our culture is shit!” Crim joined in, glaring daggers towards their host.

“Indeed, the application of your simulation is unsatisfactory.” Even Nebula, who was usually silent, had commented on the display.

“It’s a reflection of humans, not me.” Orig shrugged the angry Gasters away. “Do you have no faith in your sons?” He smugly taunts the audience before turning his back in joy. “Besides, they are knowledgeable of their option to stray from Classic. Maybe they’re not good enough?” Orig continued to offend the rest of his colleagues, satisfied by multiple angry responses.

“Orig, this is no way to treat each other. I suggest you refrain from causing more uproar unless you want to cancel this event.” Bravo had finally stepped in before Crim and Cut decided to rip him to subatomic particles.

“Alright, alright.” Orig gives a careless wave to his look-alike acquaintance. “Of course, our job is to increase the likelihood for each other. While we may be monitoring the-” Orig stopped his lengthy boast at the knock of a door.

“HELLO?” That loud yet polite voice could only mean one person. Blueberry, Tide’s son.

“Cover the equipment! Take out your retiree hobbies! We cannot let him find out!” Orig commanded the room, all of them following his order. Computers were closed, whiteboards were flipped and cats were positioned on their laps. “Rico, crochet kit!” Bravo passed a needle and ball of yarn to Orig before sliding in rocking chairs, everyone sitting in their corresponding seat.

“THERE’S A LOT OF NOISE! ARE YOU GUY ALRIGHT- OH.” Blue entered the room, seeing all the Gasters in their rocking chairs, cats/rabbits on their lap and crochet needles already working on the next knitted blanket.

“Bluey!” Tide perked up from his rocking chair, startling the kitten in his lap.

“You’re too loud, cu-” Tide death-stared Cut before he could finish off his sentence.

“DAD! GUESS WHAT?!” The blue ball of energy ran up to Tide before jumping up and down next to his father’s chair.

“What is it, son?” He patted the hyperactive skeleton’s head.

“I WAS INVITED TO A PARTY!” His pupils became star-shaped. The other Gasters watched in envy of their close relationship.

“That’s great! Actually, I prepared something exactly for this occasion…” Tide stood from his chair, passing the kitten to his son before walking to a nearby drawer.

“A KITTEN?”

“No, silly. Ah, here it is!” He pulled out a hamper of sweets and drinks. “Please share these with everyone at the party. This is sure to make the party fun!” They swapped items and Blue started to head out of the ‘retiree home’.

“YOU’RE THE BEST DAD! I’LL RETURN SOON!” 

“Have fun, Bluey!” Tide waved lovingly to his son while everyone else sighed in relief.

“That was close. Finally did something useful, Tide.” Orig dismissed the latter’s acting.

“Let’s see the statistics now! I can’t wait to see the difference.” Tide radiated optimism while watching Bravo uncover the main display. “Now those are some results I can get behind!” 

50% possibility of failure.


End file.
